Li-He Zhang

LED-based trapping may improve whitefly management, but light conditions that attract pests may also affect beneficial predators. This study evaluated how wavelength, irradiance, and temperature influence the phototactic behavior of Bemisia tabaci Middle East-Asia Minor 1 (MEAM1) and its predator Serangium japonicum (Coleoptera: Coccinellidae). Adults were tested in Y-tube assays across multiple wavelength–irradiance combinations at 25 ± 1 °C, followed by temperature-dependent experiments at 20, 25, 30, and 35 °C under selected settings. B. tabaci MEAM1 consistently showed strong positive phototaxis. At irradiances of 100, 200, 400, 600, and 800 µW cm⁻², positive phototaxis was highest under 480 nm light, whereas at 1000 µW cm⁻², it was highest under 520 nm light. For S. japonicum, negative phototaxis was highest under 440 nm at 200 µW cm⁻² and under 400 nm at 600, 800, and 1000 µW cm⁻², and this avoidance weakened as temperature increased. Under a strict predator-safe criterion, 400 nm at 600 µW cm⁻² was the best coordinated setting at 20–30 °C, whereas 440 nm at 600 µW cm⁻² was the best strict predator-safe setting at 35 °C. These results indicate that selective LED trapping should be deployed as a temperature-aware strategy rather than as a single fixed setting. The findings provide a basis for improving the compatibility of physical and biological control in B. tabaci management.

Diaphorencyrtus aligarhensis parasitizes the Asian citrus psyllid (ACP), Diaphorina citri, the primary insect vector responsible for transmitting Huanglongbing (HLB), a severe citrus disease. Screening of appropriate reference genes is a critical prerequisite for reliable RT-qPCR analysis, which is essential for investigating the functions of target genes in D. aligarhensis across diverse experimental conditions. However, to date, no validated reference genes have been reported for this species. This study assessed seven housekeeping genes in D. aligarhensis under six conditions (developmental stage, body tissue, population, temperature, diet, and starvation) using five stability algorithms (geNorm, BestKeeper, NormFinder, RefFinder, and ∆Ct). The results identified the most suitable reference genes for specific experimental conditions: EIF5A and RPL32 for the developmental stage; RPL13 and H3 for population comparisons; RPS6 and GAPDH for different feeding diets; RPL32 and RPS6 for starvation; RPL7A and RPS6 for different body tissues (head, thorax, abdomen) and temperature gradients (5 °C, 15 °C, 25 °C, 35 °C). Furthermore, the expression profiles of HSP70 were markedly different when normalized to the most versus the least stable reference genes across body tissues, diets, starvation durations, and temperatures. Our findings establish the first set of RT-qPCR reference genes for D. aligarhensis, providing a useful foundation for functional genomics research on this biological control agent.

Insects and their endosymbionts have a close mutualistic relationship. However, the precise nature of the bacterial endosymbiont-mediated interaction between host plants and whitefly Bemisia tabaci MEAM1 is still unclear. In the present study, six populations of Bemisia tabaci MEAM1 sharing the same genetic background were established by rearing insects for ten generations on different host plants, including poinsettia, cabbage, cotton, tomato, and tobacco, and an additional population was reared on cotton and treated with antibiotics. The physiological and nutritional traits of the insects were found to be dependent on the host plant on which they had been reared. Systematic analysis was conducted on the endosymbiont titers, the amino acid molecules and contents, as well as developmental and oviposition changes in the MEAM1 populations reared on each host plant tested. The results indicate that B. tabaci contained the primary symbiont Portiera and the secondary symbionts Hamiltonella and Rickettsia. In addition, the titer of endosymbiotic bacteria in females is higher than that in males. Among the MEAM1 populations reared on each host plant, the variation pattern of Portiera titer generally corresponded with changes in biological characteristics (body length, weight and fecundity) and AA contents. This suggests that changes in the amino acid contents and biological characteristics of different B. tabaci populations may be due to changes in the Portiera content and the differences in the nutrition of the host plants themselves. Our findings were further confirmed by the reduction in Portiera with antibiotic treatment. The amino acids, body size, body weight, and fecundity of B. tabaci were all reduced with the decrease in the Portiera titer after antibiotic treatment. In summary, our research revealed that host plants can affect the content of symbiotic bacteria, particularly Portiera, and subsequently affect the nutrition (i.e., the essential amino acids content) of host insects, thus changing their biological characteristics.

The effects of the foliar spraying of carbon and nitrogen on the yield and quality of fragrant rice (Oryza sativa L.) remain unknown. A two-year field experiment was conducted by using two fragrant rice varieties, Meixiangzhan 2 and Xiangyaxiangzhan, as experimental materials. Three carbon treatments (C0: 0 mg L⁻¹ glucose, C1: 150 mg L⁻¹ glucose, and C2: 300 mg L⁻¹ glucose, recorded as C0, C1, and C2, respectively) and three nitrogen treatments (N0: 0 mg L⁻¹ urea, N1: 50 mg L⁻¹ urea, and N2: 100 mg L⁻¹ urea) were employed as experimental treatments, and there were a total of nine treatments (C0N0, C0N1, C0N2, C1N0, C1N1, C1N2, C2N0, C2N1, and C2N2). The yield and quality of fragrant rice were investigated. The results show that carbon and nitrogen treatments significantly affected the yield and grain number per panicle in fragrant rice. The yields of the two cultivars under C1N2 and C2N1 were maintained at high levels. This was mainly because the C1N2 and C2N1 treatments resulted in higher grain number per panicle and grain filling percentage. Carbon and nitrogen treatments significantly increased the dry weight and photosynthesis parameters of fragrant rice. The carbon and nitrogen treatments significantly increased the protein content. The improved grain yield was related to improvements in photosynthesis and antioxidant defense as well as osmoregulation. In summary, optimized spraying of 150 mg L⁻¹ glucose and 100 mg L⁻¹ urea at the booting stage benefits yield and grain quality by regulating photosynthesis, antioxidant defense, and osmoregulation.